Control mechanism



Jan. 17, 1939. C G KRONMlLLER 2,144,587

CONTROL MECHANISM Filed Nov. 5, 1954 2 Sheets-Sheet 1 nvvav roe Carl 6.Jfronm file] Jan; 17, 1939. c, G, KRONMILLER 2,144,587

CONTROL MECHANI SM Filed Nov. 3, 1954 2 Sheets-Sheet 2 m/ VE/VZ'OE(3a)"! Gjfranmi/Zer Patented Jam 17, 1939 UNETED STATES PATENT OFFICECONTROL MECHANISM aware Application November 3, 1934, Serial No. 751,429

18 Claims.

This invention relates to control mechanisms in general, and morespecifically to a combined liquid level and pressure control mechanismfor switches, and is of particular utility in operating mercuryswitches.

An object of this invention is to provide a novel combined pressure andliquid level control mechanism for operating a switching mechanism whichis independently responsive to changes in pressure and to changes inliquid level.

Another object is toprovide a control mechanism of the class describedembodying a lost motion connection so that surges in the float chamherare not transmitted to the control device or switch.

A further object is to provide a control mechanism for operating aswitch or like mechanism which opens the switch when a predeterminedhigh pressure or a predetermined low liquid level occurs, with means forlatching the switch in open position requiring manual re-setting of themechanism for further operation.

A still further object is to provide a control mechanism that isoperated by independent means responsive to changes in differentconditions, one of said means embodying a lost motion connection, andthe other means embodying a strain release connection.

Another object is to provide a latching mechanism of novel characterwhereby a member movable to inoperative positions by changes in separateconditions may be latched in inoperative position when so moved by oneof said conditions.

A further object is to provide a control mecha- "nism of the classdescribed'having a member to mechanism with certain parts being shown inele-' vation;

Fig. 2 is a partial front elevational view looking from the left in Fig.l with the cover removed, parts shown in section, and the mercury tubeswitch shown in broken lines for clearness;

Fig. 3 is an exploded perspective view of the elements forming a part ofthe control mecha-- nism; and

Figs. 4, 5, and 6 are partial elevational views showing a portion of thecontrol mechanism in various major positions.

Although the control mechanism of this invention is capable of use indifferent types of systems, it is preferably shown and described as acombined pressure and liquid level control mechanism wherein l0designates generally a housing or float chamber which consists of afront portion II and a rear portion l2 having a gasket I3 interposedtherebetween, these portions being secured together by nut and boltarrangements M. The front portion H of the float chamber I0 has an upperopening I5 and a lower opening I 6, which openings receive pipeconnections to be attached to a device whose liquid level is to controlthe instrument. Such connections, for example, may be made to the endsof a gauge glass of a boiler so that the water level of the boiler wouldbe transmitted into the casing or float chamber III. Since the floatchamber I0 is connected to a device having a pressure contained therein,a blowoff cock is preferably secured in an opening I! formed in the rearportion l2 to prevent overstressing of the housing and breakage of theparts therein.

Located in the housing I 0 is a float l8 which is raised or loweredaccording to changes in the level of the liquid in the housing [0. Thisfloat I8 is secured to one end of a rod 19 by means of a nut 20. Theother end of the rod 19 is rigidly secured to oppositely extending arms24 and 25 by means of screws 22 and nuts 23. The arms 23 and 25 areclamped against the rod 19 by drawing up the nuts 23 on the screws 22.The ends of these arms 24 and 25 are provided with inwardly extendingpivots 26 riveted thereto for pivotally supporting the float assembly.

Secured on the inner side of the housing III by means of screws 30 is aguard 28 in the form of a U-shaped strip having an opening 29 therein'which serves as abutments to limit the upward and downward movement ofthe float IS.

A plug 3| is screw-threaded in the housing In and has secured theretoone end of a bellows 32, and the other end of the bellow 32 is securedto the rod l9, as at 33. A gasket 34 is interposed between the plug 3|and the housing Hi, the gasket 34 and the bellows 32 forming aneiiicient seal for the float chamber l0.

Secured to the outer side of the housing III by means of screws 36 is acasing 35 which has rearwardly extending flanges 31 punched out 01' theback wall thereof to receive the pivots 26 of the arms 24 and 25. Itwill be noted at this point that the arms 24 and 25 of the floatassembly extend rearwardly and are pivoted at 26 to the rearwardlyextending flanges 31 at a point intermediate the ends of the sealingbellows 32, as shown in Fig. 1. By this construction, a real benefit isobtained in that undue straining and stressing of the bellows 32 byupward and downward movement of the float I8 is eliminated by evenlydistributing the stresses throughout the bellows 32, whereby resistanceto the movement of the float l8 by the bellows 32 is substantiallydecreased.

38 is a supporting member having ears 39 by which it is secured'to theback wall of the casing 35 by means of screws 40 extended through thecars 39. The supporting member 38 has a screwthreaded opening 4| locatedadjacent the top thereof and a hole 42 located near the bottom.

43 designates a spacer in the form of a washer having an opening 44therein, which opening is larger than the opening 42 of the supportingmember 38.

45 designates a driving lever having a hole 46 in the upper portionthereof and a hole 41 located substantially in its center and ofsubstantially the same size as the hole 44 of the spacer 43. Extendinglaterally from the driving lever 45 is a projection 48, and extendingdownwardly from the driving lever 45 is another projection 49. A movableprojection 50 extends downwardly from the driving lever 45 and ispivotally secured to the lower portion thereof by means of a screw 5|.The projection 50 is normally urged in a counterclockwise direction, asviewed in Fig. 2, by means of a tension spring 54 being secured betweena pin 52 located on the projection 50 and a. pin 53 located on thedriving lever 45. Counter-clock wise movement of the projection 50 islimited by means of a lug 55 integral with the projection 50 whichengages an abutment pin 56 on the driving lever 45. This construction,as will be more fully pointed out hereafter, formsastrainreleasewhich isa, vital feature of this invention. The top of the lever 45 is notchedas at 51 to cooperate with a latch 1|, as will be more clearly pointedout hereafter.

A mercury switch clip supporting member 58 has a hole 59 ofsubstantially the same size as the hole 61 of the driving lever 45 andis also provided with forwardly projecting lugs 6h. The upper portion ofthis mercury switch clip supporting member 58 is provided with avertical notch 6|.

A mercury switch clip 63 has a hole 65 of the same diameter as the hole5d of the mercury switch clip supporting member 553 and is adapted toengage the supporting member 58 between the forwardly extending lugs 6dthereof. The mercury switch clip 83 has spring fingers 56 adapted toreceive a mercury switch tube it.

66 designates generally a special form'oi rivet havingta; head 51, ashoulder 58 adapted to fit in the holes 65, 59, 11, and 5d of themercury switch clip the mercury switch clip supporting member 53, thedriving lever G5, and the spacer lt, repectively, and an extension iiadapted to fit in the hole of the supporting member The parts abovedescribed are assembled by placing the mercury switch clip the mercuryswitch clip supporting member the driving lever and, the spacer l -3 onthe shoulder oi the rivet GE, and by inserting the extension of therivet 563 through the hole of the porting member 38 and riveting overthe end of the extension 69. In this manner, the parts are pivotallymounted on the supporting member 38.

10 designates an eccentric rivet riveted in the hole 46 of the drivinglever 45, its head lying in the notch 6| of the mercury switch clipsupporting member 58, whereby turning of the eccentric rivet 10angularly adjusts the mercury switch clip supporting member 58 andconsequently the mercury switch tube 16 with respect to the drivinglever 45.

The latch 1| which cooperates with the notch 51 of the driving lever 45has an upstanding arm 12 extending through a slot 15 in the top wall ofthe casing 35. The latch 1| is secured to and spaced from the supportingmember 38 by means of a spacer 14 and a screw 13 extending into thescrew-threaded opening 4| of the supporting member 38. The lower portionof the latch 1| is heavily weighted so that the latch 1| is at all timesurged in a counter-clockwise direction, or latching position, bygravity.

The mercury switch tube 16 which is mounted in the spring fingers 64 ofthe mercury switch clip 63 is provided with conventional contacts 11 solocated therein that when the tube is tilted ina clockwise direction thecontacts are engaged by the usual mercury contained in the tube 16 toclose an electrical circuit, and when the tube 15 is rotated in acounter-clockwise direction the mercury disengages the contacts 11 toopen the electrical circuit. The contacts 11 are connected to fiexiblelead wires 18 which extend to and are secured to a terminal block 19, asshown in Fig. 1.

Riveted on the pivoted arm 24 of the float assembly is an actuating pinwhich extends outwardly and below the projection 48 of the driving lever45 so that upon downward movement of the float l8 in the float chambercaused by lowering of the liquid level therein, pin 80 is raised tocontact projection 48 of the driving lever 45 to rotate the drivinglever 45 in a counterclockwise direction to open the circuit in themercury tube switch 15.

82 designates a pressure pipe which is adapted to be secured to a sourceof pressure that is also to control the operation of the instrument. Thepressure pipe 82 may conveniently be secured into the float chamber II]to convey the pressures existing therein. If the float chamber I0 isprovided with a pressure blow-ofi cook, the pressure pipe 62 may beconnected to the high pressure side of the blow-off cook. The pressurepipe 82 is screw-threaded in a plug 83 which is riveted and soldered toa pressure casing 84, which pressure casing 84 is secured to the lowerwall of the casing 35 by means of screws 8|. A pressure responsivebellows 85 is located within the pressure casing 85 and is suitablysecured at its upper end to a plate 85 soldered to the pressure casing85 and is secured at its lower end to a plate 81 that carries a plunger88. Secured to the upper end of the plunger 88 is an adjustable actuator89 having a pivot point 90.

The pivot point 9% of the plunger 88 engages a concave member 93suitably secured to a lever The lever 92 has concavo-convex portionswhich engage knife edges l of a knife edge supporting member Thesupporting member 95 is rearwar-dly provided with a flange 96 which isriveted to the back wall of the casing 35 rigidiy to support the knifeedge supporting member $52. The supporting member 55 has outwardlyextending lugs 91 adjacent the "nife edges which encompassed by arms9531 of the lever 92 to maintain the parts in their assembled relation.

The lever 92 is punched out as at 99 to form a means for securing oneend of a tension spring 500 to the lever 92. The other end of thetension spring I00 is secured to a grooved nut IOI which isscrew-threaded on a screw I02 that extends upwardly through the upperwall of the casing 35, the head I03 of the screw I02 engaging the outersurface of the casing 35. By turning the screw I02 by means of theexternal screw head 603, more or less tension may be placed in thespring I00. Riveted to the side wall of the casing 35 is a stop membercomprising an upper 'stop I04 and a lower stop I05 to limit the amountof movement of the lever 92.

From the above it is seen that the tension spring 900 urges the lever 92in a counter-clockwise direction about the knife edges 94, and that thepressure bellows 85 urges the lever 92 in a clockwise direction aboutthe knife edges 94, the upper and lower stops I04 and I05 limiting suchcounter-clockwise and clockwise movements of the lever 92.

Integral with and extending upwardly from the lever 92 is an actuatingarm I08 that is provided with a forwardly extending pin I01 whichextends between the downwardly extending projections 49 and 50 of thedriving lever 45. By this construction the pin I01 normally engages-thedownwardly extending projection 50 and, through the spring 54, urges themercury switch 16 in a. clockwise direction to maintain the electricalcircuit closed when the force in the spring I00 is greater than thepressure acting on the bellows 85. The spring 54 is so chosen that it isof just suillcient strength to overcome the friction of the moving partspivoted on the rivet 68. When the pressure as conveyed by the pipe 82increases so that it overcomes the force in the spring I00, pin I01 ismoved to the right to engage downwardly extending projection 49 of thedriving lever 45 to rotate the switch 16 in a counterclockwise directionto open the circuit,

Mounted on both side walls of the casing 24 are U-shaped brackets havinga rear arm I08 to which is secured the terminal block 19 by means ofscrews I09 and a front arm IIO to which is secured the cover II2 bymeans of screws III.

The operation of the control mechanism is as follows: when the liquidlevel in the float chamber I0 is at a proper height, the float I8 ismaintained in its upper position, and the pin is out of engagement withthe projection 48. When the pressure is normal, the spring I00 maintainsthe lever 92 against the stop I04 and the pin I01 against the downwardlyextending projection 50 of the driving lever 45 to maintain the switchin closed or operative position, as shown in Fig. 6.

When the pressure as conveyed by pipe 82 becomes excessive it acts uponthe bellows to overcome the tension in the spring I00 to force the lever92 against the lower stop I05 to move the pin I01 to the right intoengagement with the downwardly extending projection 49 of the drivinglever 45 to move the switch 16 in a counter-clockwise direction toinoperative or circuit open position, as shown in Fig. 5. It will benoted in Fig. 5 that the laterally extending projection 48 has movedaway from pin 80.

Assuming that the pressure as conveyed by pipe 82 is normal, the pin I01engages the downwardly extending projection 50 of the driving lever 45to maintain the switch in its closed or operative position, but when thelevel of the liquid in the float chamber I0 becomes abnormally low, thefloat I8 moves downwardly to move pin 80 upwardly into engagement withthe laterally extending projection 48 of the driving lever 45 to rotatethe switch in a counter-clockwise direction to inoperative or openposition, as shown in Fig. 4. Because of the fact that the pressureacting on the bellows 85 is normal, some means must be provided to allowthis movement of the switch to inoperative position by the pin 80. Thismeans is accomplished by use of a strain release in the form of thetension spring 54 which is sufiiciently strong normally to urge theswitch to circuit closed position, but not strong enough to overcome theaction of the pin 80 as it is moved upwardly by a lowering of the levelof the liquid in the float chamber I0. Fig. 4 shows the spring 54 in itsstrained position and clearly sets forth the operation of the strainrelease connection between the pressure actuated pin I01 and the drivinglever 45 Whenever the driving lever 45 is moved sufliciently far in acounter-clockwise direction, the latch 1I drops into the notch 51 of thedriving lever 45, holding the driving lever 45 in that position untilthe latch TI is manually released by means of the handle 12. The drivinglever 45 is so moved into latching position when an undesirably lowliquid lever exists in the float chamber I0. Float I8 lowers and raisespin 80 which engages the projection 48 to move the driving lever 45 in acounter-clockwise direction to permit the latch H to engage in notch 51.However, the

driving lever 45 is not moved into latching posltion upon a rise inpressure acting on the bellows 85 because the bottom stop I 05 limitsthe clockwise movement of the lever 92 and the consequentcounter-clockwise movement of the driving lever 45. By reason of thelower stop I05, the driving lever 45 cannot be moved sufliciently far toallow the latch H to drop into notch 51.

From the above construction and operation a very desirable result isobtained in that upon low liquid level and for high pressure the switchis opened, and it may be automatically closed when the liquid level andthe pressure return to their proper values, but when the liquid levelbecomes abnormally low the switch is latched in open posi-.

tion requiring manual intervention to allow the switch to be closed.

If the control system of this invention should be applied in a systemwhere it would be advantageous to latch the switching mechanism in anopen or inoperative position upon the existence of an abnormally highpressure acting on the bellows 85, the lower stop I05 could be loweredto permit further counter-clockwise movement of the driving lever 45whereby the latch 1I could engage in the notch 51.

If it is desired to have the control mechanism automatically resumeoperation both when the liquid level has been restored and when thepressure as conveyed by pipe 82 has been decreased,

the latching mechanism 1I may be omitted entirely. When the latchingmechanism is so omitted, the control mechanism is completely automaticin its operation.

From the above it is seen that I have invented a combined liquid leveland pressure control for operating a device such as a swltch wherein thedevice or switch is moved to an open or inoperative position by anabnormal condition existing in the float chamber or by an abnormalcondition of pressure, and wherein these changes in conditions actindependently of each other on the control mechanism.

While one embodiment of this invention has been shown and described, itis obvious that many modifications may be apparent to one skilled in theart, and consequently this invention is to be limited only by the scopeof'the appended claims and the prior art.

I claim:

1. In a device of the character described, a float chamber, a float insaid float chamber and adapted to be raised or lowered by changes inliquid level in said chamber, a bellows adapted to be.

expanded and contracted by changes in pressure, a switch movable tooperative and inoperative positions, a pivoted lever for moving saidswitch, a fixed projection on said lever, a pin operatively connected tosaid float to engage said projection to move said switch to inoperativeposition when said liquid level reaches a predetermined minimum, asecond fixed projection on said lever, a second pin operativelyconnected to said bellows to engage said second projection to move saidswitch to inoperative position when said pressure reaches apredetermined maximum, a resilient projection on said lever to beengaged by said second pin normally to maintain said switch in operativeposition when said pressure ing means associated with said lever tomaintain said switch in inoperative position when said switch is movedto inoperative position by one of said pins.

2. In a device of the character described, a float chamber, a float insaid float chamber and adapted to be raised or loweredby changes inliquid level in said chamber, a bellows adapted to be expanded andcontracted by changes in pressure, a switch movable to operative andinoperative positions, a pivoted lever for moving said switch, a fixedprojection on said lever, a pin operatively connected to said float toengage said projection to move said switch to inoperative position whensaid liquid level reaches a predetermined minimum, a second fixedprojection on said lever, a second pin operatively connected to saidbellows to engage said second projection to move said switch toinoperative position when r adapted to be raised and lowered by changesin means operatively connected to said float and liquid level in saidchamber, a bellows adapted to be expanded andcontracted by changes inpressure, a switch movable to operative and inoperative positions, amember for moving said switch,

associated with said member to move said switch to inoperative positionswhen said liquid level reaches a predetermined minimum, meansoperatively connected to said bellows and associated with said member tomove said switch to inopertive position when said pressure reaches apredetermined maximum and to maintain said switch in operative positionwhensaid pressure is less than said predetermined maximum but allowingsaid switch to bemoved to inoperative position by said first mentionedmeans, and means associated with said member to maintain said switch ininoperative position when said switch is moved to inoperative positionby one of said means. I

4. In a device of the character described, a float chamber, a float insaid float chamber and adapted to be raised and lowered by changes inliquid level in said chamber, a bellows adapted to be expanded andcontracted by changes in pressure, a movable control member, aprojection on said control member, a. pin operatively connected to saidfloat to engage said projection to move said controlmember in onedirection when said liquid level reaches a predetermined minimum, asecond projection on said control member, a second pin operativelyconnected to said bellows to engage said second projection to move saidcontrol member in the same direction when said pressure reaches apredetermined maximum, a resilient projection on said control member tobe engaged by said second pin to move said control member in a seconddirection when said pressure maintain said control member in its shiftedposition when moved in said first direction by one of said pins. 1

5. In a device of the character described, a fioat chamber, a float insaid chamber and adapted to be raised and lowered by changes in a liquidlevel in said chamber, a bellows adapted to be expanded and contractedby changes in pressure, a movable control member, means operativelyconnected with said float and associated with said control member tomove said control member in one direction when said liquid level reachesa predetermined minimum, means operatively connected to said bellows andassociated with said control member to move said control member in thesame direction when said pressure reaches a predetermined maximum and'tomove said control member in a second direction when said pressure isless than said predetermined maximum but allowing said control member tobe moved in said first direction by said first mentioned means, andmeans associated with said control member to maintain said controlmember in it's shifted position when moved in said first direction byone of said means.

6. In a device of the character described, a movable control member,means responsive to changes in a liquid level to move said controlmember in one direction when said liquid level reaches apredeterminedminimum, means responsive to changes in pressure to movesaid control member in the same direction when said pressure reaches apredetermined maximum and to move said control member in a seconddirection when said pressure is less than said predetermined maximum butallowing said control mem- -ber to be moved in said flrstdirection bysaid first mentioned means, and means associated with said controlmember to maintain said control member in its shifted position whenmoved in said first direction by one of said means.

'1 In a device of the character described, a switch movable to operativeand inoperative posithus, a member for moving said switch, meansresponsiveto changes in liquid level associated with said member to movesaid switch to inopera- A tive positiommeans responsive to changes inpressure associated with said member to move said switch to inoperativeposition and to maintain said switch in operative position during normalpressure conditions but allowing said switch to be moved to inoperativeposition by said first means, and means associated with said member tomaintain said switch in inoperative position when said switch is movedto inoperative position by one of said means.

8. In a control mechanism, a movable control member, means responsive tochanges in a condition for moving said member to a first position, meansresponsive to changes in another condition to move said control memberto said first position and normally to maintain said control member in asecond position but allowing movement 01' said control member to saidfirst position by said first means, and means associated with saidcontrol member to maintain said member in said first position when movedto said first position by one of said means.

9. In a control mechanism, a switch movable to open and closedpositions, means responsive to normal pressure conditions normally tomaintain said switch in closed position and to move said switch to openposition in response to abnormal pressure conditions, means responsiveto abnormal-liquid level conditions to move said switch to open positionindependent of said pressure conditions, and means to latch said switchin open position.

10. In combination, a member to be controlled and movable in first andsecond directions, latching means associated with said member to becontrolled and operative to latch said member to be controlled whenmoved sufllciently far in said first direction to then prevent returnmovement thereoi. in said second direction, first and second actuatorsassociated with said member to be controlled and both operative to movesaid member to be controlled sufllciently farin said first direction tocause the same to be latched by said latching means, and restrainingmeans associated with one of said actuators to prevent the same frommoving said member to be controlled sufiiciently far in said firstdirection to cause latching thereof.

11. In combination, a movable control member,

a projection on said control member, means ineluding a pin for engagingsaid projection to move said control member in one direction, a secondprojection on said control member, means including a second pin forengaging said second projection to move said control member in the samedirection, and-a resilient projection on said control member to beengaged by said second pin to move said control member in a seconddirection and adapted to yield when the control member is moved in thefirst direction by the first pin.

12. In combination, a movable control member, a projection on saidcontrol member, means including a pin for engaging said projection tomove said control member in one direction, a second projection on saidcontrol member, means including a second pin for engaging said secondprojection to move said control member in the same direction, aresilient projection on said control member to be engaged by said secondpin to move said control member in a second direction and adapted toyield when the control member is moved in the first direction by thefirst pin, and means associated with said control member to maintainsaid control member in its shifted position when moved in said firstdirection.

13. In combination, a movable control member,

abutment means on said control member, means for engaging said abutmentmeans to move said control means in one direction, second abutment meanson said control member, second means for engaging said second abutmentmeans to move said control means in the same direction, yieldableabutment means on said control member to be engaged bysaid second meansto move said control member in the other direction and. adapted to yieldwhen the control member ismoved in the first direction by the firstmeans, and latch means associated with said control member to hold saidcontrol member in its shifted position when moved in said firstdirection by said first abutment means, said latch means remaininginoperative when said control member is moved by said second abutmentmeans.

14. In combination, a movable control member, abutment means on saidcontrol member, means for engaging said abutment means to move saidcontrol means in one direction, second abutment means on said controlmember, second means for engaging said second abutment means to movesaid control means in'the same direction, yieldable abutment means onsaid control member to be engaged by said second means to move saidcontrol member in the other direction and adapted to yield when thecontrol member is moved in the first direction by the first means, andmeans associated with said control member to maintain said controlmember in its shifted position when moved in said first direction.

15. In combination, switch means movable to open and closed positions,pressure responsive means operable to move said switch means to open andclosed positions respectively upon the achievement of predetermined highand low pressures, liquid level responsive means operable to move saidswitch to open position upon the achievement of a predetermined lowliquid level, latch means associated with said switch means operable tohold the same in open position when moved by said liquid levelresponsive means upon the achievement of said low liquid level and meansassociated with said pressure responsive means for preventing it fromlatching said switch means in open position upon achievement of saidpredetermined high pressure.

16. In combination, a control member, first means for controlling themovement of said control member in either of two directions, second.means for controlling the movement of said control member in either oftwo directions, latch means positioned to be engaged by said controlmember when moved a predetermined amount in one direction by one of saidmeans, and means preventing the other of said control means from movingsaid control member far enough to engage said latch means.

17. In a device of the character described, a float chamber, a float insaid fioat chamber and adapted to be raised and lowered by changes inliquid level in said chamber, a bellows adapted to be expanded andcontracted by changes in pressure, a movable control member, aprojection on said control member, a pin operatively connected to saidfioat to engage said projection to move said control member in onedirection when said liquid level reaches a predetermined minimum, asecond projection on said control member, a second pin operativelyconnected to said bellows to engage said second projection to move saidcontrol member in the same direction when said pressure reaches apredetermined maximum, and a resilient projection on said control memberto be engaged by said second pin to move said control member in a seconddirection when said pressure is less than said predetermined maximum andadapted to yield when said control member is moved in the firstdirection by said first pin.

18. In combination, a movable control member, I

pressure responsive means for moving said control member in onedirection, liquid level responsivemeans for moving said member in thesame direction and means for latching said member in its shiftedposition when moved by said liquid 5 level responsive means.

' CARL G. KRONMILLER.

